Visual stimuli can evoke complex behavioral responses. The nature of each response is dependent upon the identification of salient cues in the environment, the integration of multiple cues in the form of a behavioral decision, and the performance of a selective motor output. Complex neuronal circuits identify, analyze and integrate many types of visual cues. Remarkably, we have only a very limited understanding of the logic by which such circuits function to guide behavior in any context. We will investigate how neurons sensitive to visual motion guide motion-evoked behaviors, using the Drosophila visual system as a model. First, using genetic silencing techniques, we will determine the roles of different photoreceptor classes in motion perception. Next, we will employ enhancer-trap methodologies to identify specific neurons involved in processing motion cues. Finally, we will use standard genetic techniques to elucidate the anatomical and molecular correlates of motion circuits. As adult patients who had infantile deficits in binocular vision, such as those associated with amblyopia and strabismus, frequently display defects in processing visual motion, understanding the structure and function of circuits involved in motion vision may suggest new therapeutic strategies to ameliorate the symptoms associated with these conditions. [unreadable] [unreadable] [unreadable]